The cryptocurrency Bitcoin recently surged above $19,500 a unit for a short time, briefly surpassing the “tulip mania” of the Netherlands in the 17th century to become the biggest recorded asset bubble in the history of Western civilization. That caused a number of participants in that space to slip into “irrational exuberance” mode, going to such extremes as not only buying Bitcoin with their credit cards but also taking out mortgages to snap up as much of the cryptocurrency as they possibly could ...